Computerised Tomography (CT)

What is a CT Scan?

Computerised Tomography (CT) is an x-ray examination performed with a computerised x-ray scanning machine.

The CT scan looks at the body in cross section. To produce images, a narrow beam of x-rays is rotated around the part of your body to be examined. The x-ray beam is monitored and recorded by an array of sensitive detectors which channel the signals to a large computer within the scanner. The computer then generates a visible image of the cross section of the body region being examined.

What happens before the CT scan?

You will need to make an appointment for the examination. When you make the appointment, you will be told if any preparation is required. You may be asked to fast or to drink oral contrast prior to the study.

We may ask you to remove your hairclips, earrings, pins, chains or other items of jewellery before the examination, as these can sometimes interfere with the scan. We may also need you to change into a gown, depending on the type of examination being performed.

Sometimes an intravenous injection of contrast material will be required, depending on the area being examined. The contrast can provide valuable information by highlighting certain organs and blood vessels on the CT images. As with any medication or injection, there is a small chance of an allergic reaction to the contrast. The radiographer performing the examination will go through this with patients before the scan. Please tell staff if you have had any form of reaction to contrast before.

During the injection you may notice a brief sensation of warmth and a metallic taste. These subside rapidly.

What should I bring?

Please be sure to bring along any previous x-rays, CT scans, ultrasound or MRI examinations which you may have available. These films can often provide valuable additional information to the attending Radiologist when your scan is reported. All films are your property and will be returned to you.

Also, please bring your request form from your doctor which instructs us as to why the scan has been requested.

What happens during the CT scan?

For the scanning procedure, you will be asked to lie on the scanner table. The part of your body to be examined will be positioned in the scanner opening. You will hear a humming noise when the scanner’s x-ray beams rotate around you, but no moving parts will touch you. There will be no discomfort.

Most CT scans take 10-15 minutes to perform.

During the scan, the technician can see and hear you at all times, as there is a 2-way microphone built into the scanner. It is unusual for patients to feel claustrophobic during a CT scan.

What happens after the CT scan?

After the scan, you are free to eat and drink normally. If you have had an injection, the contrast is absorbed and passed out of your body in your urine during the next 8 to 10 hours. Drinking plenty of fluid will assist this.

You should be able to drive a car and return to your normal activities. There are no after effects.